Here's ones I have made before:

A slice of hard salami, folded into a triangle
A slice of deli pepperoni, folded into a triangle
A cube of provolone
Black and green olives
Pieces of tomato (or you can use cherry but they don't absorb the dressing so I don't recommend)
Red onion slice
Two pieces of tortellini or other durable pasta

Dressing:
1/2 cup Olive Oil
1/4 cup Balsamic Vinegar
1 tbsp. Basil
1 tbsp. Oregano
1 tsp. salt
1 tsp. pepper

I put the skewers in a large tupperware container and pour the dressing over them and let them marinade overnight or at least for several hours, shaking them up often and sometimes I drizzle a little vinegar before serving depending upon how much dressing was absorbed.